


Congrats, You're A Dad!

by NonstopCreatorOfNonsense



Category: Undertale (Video Game)
Genre: Alternate Universe, Alternate Universe - Canon, Alternate Universe - Children, Alternate Universe - Parents, Animal Instincts, Babybones (Undertale), Children of Characters, Ecto-Body (Undertale), Family Fluff, Fatherhood, Feral Behavior, Fluff, Fluff and Humor, Gen, Gill Papyrus, M/M, Neptune Sans, Original Character(s), Originally Posted on Tumblr, Parent Sans (Undertale), Parenthood, Underlust Sans (Undertale), Unplanned Pregnancy
Language: English
Status: Completed
Published: 2020-12-22
Updated: 2020-12-22
Packaged: 2021-03-22 05:00:35
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,698
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/30033414
Author URL: https://archiveofourown.org/users/NonstopCreatorOfNonsense/pseuds/NonstopCreatorOfNonsense
Summary: Lust had vanished for a while without a warning or explanation, and Nep had begun to think it was because he'd gotten tired of him. When Lust returns several months later, Nep discovers that he couldn't have been more wrong
Relationships: Neptune Sans & Gill Papyrus, Underlust Sans/Neptune Sans





	Congrats, You're A Dad!

“Neptune?… Neptune, are you there? _Please,_ it’s really important that we talked! Please come out of there!”

The eldest of the lake dweller brothers hesitated, remaining hidden under the dock as he contemplated his decision. Deal with the purple clad whore again today, or lay low and wait for him to leave. Upon hearing a much higher pitched voice call out in what he immediately recognized as the cry of an infant, he jerked in surprise, making a face in confusion. What the _actual hell_ was going on now???

Nep drew in a deep breath, peeking over the side of the dock and watching as Lust made himself comfortable on a small patch of green grass, a tiny, rather fragile looking babybones in his arms and swaddled in what looked like some sort of blanket. The baby in his arms wiggled and cried, and he frowned, gently rocking the child in an attempt to soothe it, and when it seemed the baby couldn’t be soothed, Lust let out a shaky breath, his voice soft, “Hey, hey… Shhh… Don’t cry, baby… It’s ok, it’s ok. Mama’s here, Mama’s got you, Betta, it’s ok.” Nep blinked in surprise; _“Mama”?_ He’d thought it before, but it would forever be a question that spiraled in his mind: What the _fuck?_

Careful to keep his distance from the pair, the lake dweller hoisted himself up onto the dock, clearing his throat to announce his presence before he spoke, “…So. How’s parenthood treating ya?” Lust was momentarily startled, his sockets widening before he relaxed again and sighed deeply, offering the other an exhausted smile, “Other than the _crying_ and _dirty diapers_ , it’s really not that bad.” Nep fell silent, unconsciously beginning to edge closer to the pair. Breaking the silence, Lust glanced between the lake dweller and the infant in his arms, almost appearing nervous, “I uh… We need to talk, Neptune. Please, it’s really, _really_ important.” The skeleton monster in question made a sound of acknowledgement, “Yeah?… What’s up, shithead? You’ve been away for a while now, and I almost kinda started wonderin’ if ya went and got bored a’ me yet.” Lust shook his head, laughing weakly as the baby in his arms kept crying, despite the gentle rocking, “No, no, not at all… I just thought you might not wanna see me all pregnant and swollen… As it turns out, ‘round’ isn’t really a good look on me.” He shifted the baby, using his now free hand to lightly pat the ground beside himself before he continued, “I _did_ want you to meet this little beauty though… She’s yours, after all.” 

Nep stared at Lust for a moment, clearly at a loss. When the words and their meanings began to finally register, he made a face, gesturing to himself, “Wait, wait, wait, _hold up_. You’re tellin’ me that _my ugly mug_ when and made somethin’ tiny and fragile like _that?”_ He pointed at the baby for emphasis, and Lust nodded, humming in confirmation, “Mhm… This little thing is alive right now because of you. You’re her dad, Neptune… You should see her during bath time, she looks _just like you.”_ Nep physically couldn’t stop himself from scooting closer, on his hands and knees as he leaned forward to begin sniffing the child. Sure enough, he _did_ smell traces of himself on her.

The baby suddenly sneezed and he flinched, jumping back and staring at her with wide sockets, his body rigid. Lust laughed softly, playfully arching a brow bone, “Why so jumpy, Angelfish? It’s just your daughter, Betta.” Nep scrunched up his face, hesitating for a moment as the infant went back to crying, “…Put her in the water. If she’s _really mine,_ she’ll stop with all the fussin’.” Lust seemed unsure for a fraction of a second, before he nodded slowly, gently removing the infant from her swaddle. Setting the bundle of cloth aside, he also removed her ridiculously tiny socks and his shoes before rolling his pants up, and as he moved closer to the lake with her in his arms, the lake dweller follower, practically at his side and watching like a hawk.

Nep got into the water again, his solid white sockets locked on baby Betta as Lust leaned down, gently letting her legs dangle in the luke warm pond water. To both of their shock and utter amazement, her crying died down, her legs beginning to kick at the water. She began trying to bounce, cooing and squealing as she looked down at her reflection. The lake dweller eased closer to her again and Lust took a deep breath, watching him closely; Nep didn’t _seem_ to be displaying any sort of aggression, and he showed no signs of attacking, which meant this was going _well_. Lust tried to shake the image in his head of a visit when he’d found a set of bloodied, shredded children’s clothes on the shore, a set of small shoes discarded nearby.

Visibly curious, Nep leaned closer to sniff at Betta’s face again, and the infant blinked in surprise, cooing as she made a face at him. He tilted his head and she copied him, tilting hers as she screeched and kicked at the water again, sending a small amount rippling in his direction. His soul twisted within his chest and he furrowed his brow bones, hesitantly glancing up at Lust and asking, “…Can I… Can I hold her? Just for a minute, please?” Lust nodded, offering him a reassuring smile, “Of course… Just for the record, you _do know_ how to hold a baby, right?” The lake dweller scoffed, “Excuse you? I’m not _dense_ , y’know. I’ve held _plenty_ of babies before.” Lust bit back a retort and made a soft sound of acknowledgement, “Alrighty then… Just… Be careful. Please.” 

The lake dweller made a sound back in confirmation, gently taking his daughter from Lust and lifting her up into his arms, and to Lust’s amazement, cradled her against his chest. The infant stared up at him with wide eyes, her violet eye lights settling on his sharpened teeth. She scrunched up her face as if trying to process something, and Nep stared in surprise as her own ordinary teeth grew sharper, mimicking his. Finally reaching acceptance of the situation, he smiled slightly and let out a deep sigh, his voice low, “Well with a face like that, I guess you _really are_ my kid, huh?” One of her tiny hands lightly patted his face and he shifted back into the appearance of a normal Sans, his eye lights flickering and becoming tiny hearts as she copied him again, once again looking like a normal babybones.

One of his clawed hands moved to carefully touch her face and she cooed, smiling brightly up at him and wiggling in his grasp. Before he could process what he was doing, he leaned down, delicately pressing his teeth to her forehead and nuzzling her face affectionately. Watching quietly, Lust’s anxiety faded into relief and he smiled softly, gently placing a hand on his chest. He knew there was a _pretty significant_ risk to this, and with having it go so _smoothly_ , saying he was glad would be a _severe_ understatement. Everything was silent for a brief moment before Lust cleared his throat, “Hey, uh… Where’s your brother? Wouldn’t he like to meet Betta too?” Being brought back to the present moment, Nep nodded and hummed, “Yeah, probably. If ya wanna take the kid for a sec, I can go get ‘em.” Lust made a sound of agreement, gently taking back their daughter and holding her close to himself, “Ok, I can do that.” Nep, overcome by a surge of unexpected emotions, suddenly donned an uncharacteristically giddy grin, pressing his teeth to Lust’s and stealing a quick kiss before disappearing back underwater. Lust’s cheekbones immediately became stained purple and his eyes were wide in surprise; well _that_ was new. Unless it was one of their… _Meetings_ , Neptune normally didn’t show much interest in kissing.

It wasn’t long before Nep returned, a much taller skeleton emerging from the water close behind him. Lust and Gill, the youngest of the two lake dwellers, exchanged friendly hellos, before Lust carefully handed the infant to him, giving him some gentle instructions to make sure the taller knew what exactly to do. Gill seated himself on the edge of the dock, the baby flush against his chest as he gazed down at her in a mix of wonder and affection. Leaning down to sniff at her in a manner similar to what Nep had done, the faint scent of his brother on her gave him all the reassurance he needed. He smiled at her, trying to keep his normally boisterous voice down as to not scare her, “Hello There, Betta! You’re So Tiny And Cute, My Goodness Gracious! It’s Hard To Believe _My Brother_ Had Any Part In Making You!”

Nep scoffed at the comment, rolling his eyes and attempting to shrug off the sound of Lust’s soft giggling. Betta squealed and smiled widely up at her uncle, reaching out to gently pat at his face, kicking her legs excitedly. In response, Gill’s long legs began to sway back and forth, swishing at the water as he smiled widely back, offering her praise as he gently touched her tiny hand. Watching the pair with a smile, Lust sighed softly; When it came to Gill, he hadn’t been worried at all whatsoever. Gill was just another Papyrus. Being the same as his own brother, Lust was confident in himself when he’d decided that Gill was of no real threat. Not to himself, not to Betta, not to anyone, for that matter. 

Well, as long as they weren’t swimming in the lake, at least. Aside from what happened underwater, Gill was harmless.

* * *

Some years had passed since meeting Betta; She was now a whole six years old, and _much more_ energetic than her parents had been prepared for. Setting her overnight bag aside, Nep curled up on the bed beside her, opening a book and allowing the child to cuddle up against his side; Being so young, he wasn’t sure he wanted her to spend all of her time in the water yet, so he’d taken the liberties of setting up a nesting area in his underground bunker. A bed had been made, he’d gathered toys from campers that’d brought their families, he’d even stolen clothes from them that he thought might fit his daughter. A box with snacks piled into it sat nearby, beside an old refrigerator he’d repaired and gotten set up. Everything she needed was here; A bed, spare clothes, food, toys, books, all of it. 

Betta eagerly prompted him to begin reading her favorite book, and he caved, starting to read with a small smile, “Once upon a time, there were a pair of little bunny brothers. One was born with golden fur, while the other was born with grey and black speckled fur. The little golden bunny loved the sunshine, and he loved to play outside with his friends, the ducks and mice. The grey and black bunny loved the darkness, and he loved reading in the den, by himself. They were as different as night and day, but they loved each other very much. The little golden bunny’s friends didn’t like the darker brother very much though, so they never invited him to play. The golden bunny tried getting him brother to play outside with them, but because he knew he was not wanted there, he always said no.” 

The child frowned, furrowing her brow bones and listening quietly as he continued, “The grey and black bunny got lonely after a while. He began to want friends too, but nobody liked him. Because he was born with a darker fur color, they all thought he was bad. The little golden bunny knew this wasn’t true, and he always told them to stop talking about his brother that way. His brother was good, and they just hadn’t seen it yet.” Betta interrupted, her eyes wide and full of worry, “They make friends with the darker bunny, don’t they, Daddy? He won’t be alone _forever,_ will he?” Nep paused, shaking his head and glancing at his daughter, offering her a small, reassuring grin, “No, Sweetheart. He won’t be alone forever in the end… He’s always gonna have his bro, no matter what.”

The child seemed to accept this answer, falling silent and allowing him to continue again. They progressed further throughout the story, “One day, there was a great fire. The little golden bunny’s friends looked everywhere, but they could not find him. The little golden bunny was trapped, fire everywhere around him. Just when things weren’t looking so good, his brother showed up. The little grey and black bunny got him out, ignoring his own pain as a patch of his dark fur was eaten away by the flames. Burnt and scarred now, he dragged his golden bunny brother out into the sunlight, his normally beautiful fur now covered in soot. He stayed beside his brother, getting him away from the fire and to safety, and the other animals saw this. They couldn’t believe he’d risked his life, and they couldn’t believe how wrong about him they’d been.” 

Betta tried to muffle a yawn and Nep lightly nuzzled her head, his rough voice soft, “The grey and black bunny was not bad. He was good. Very good. They were sad that they’d all judged him so wrongly, and as he worked to help his brother heal, they offered him their friendship. He’d never had any friends before, and before he knew it, he was crying. He was crying because he was happy. His heart swelled in joy, and he accepted. They became friends with him, and from that day on, the little bunny brothers were both happy. They made many more friends together, and they lived happily ever after.” As his daughter curled into him, Nep wrapped an arm around her, setting aside the book and sighing softly. She rubbed her eyes tiredly, and Nep murmured, “Goodnight, Betta… Sweet Dreams, kiddo.” Her voice was laced with sleepiness as she replied, “Goodnight, Daddy… I love you…” The lake dweller’s expression softened and he pressed a soft kiss to her head, “I love you too, Sweetheart… I love you _so much…”_

The next morning, Lust made his way into the underground bunker, able to locate the two with only minimal difficulty. Peering around a corner at the bed they’d fallen asleep on, he paused, a soft breath leaving him as he touched his sternum through his shirt; Nep was curled up on his side and snoring softly, while Betta was cuddled close to him, one of his arms wound loosely around her. She clung to his shirt, her face buried in the fabric as she slept, completely at ease. Sneaking his phone out of his pocket, Lust was quick to snap a few pictures, checking them over again before putting the device away. Satisfied at having gotten some cute pictures of them, he very lightly knocked on the wall a few times, staying silent as Nep’s sockets fluttered open. As the lake dweller’s gaze fell on him, he offered the taller a small smile and waved, and Nep tiredly waved back, too tired to form words yet.

Moving slowly, Lust made his way over to the bed and sat on the edge beside the father of their child. Nep offered no complaints and didn’t budge, not even as he felt Lust’s hand begin to gently caress his skull. Drawing soft purrs from the lake dweller, the Underlust skeleton smiled to himself, unable to fight to urge to lay down and cuddle up to him as well. As the shorter of the two pressed against him, Nep sighed, feeling himself starting to doze off again. Hearing the lake dweller begin to snore softly again, Lust rolled his eyes; At this rate, they’d be in bed all day. Not that he could complain though. He closed his eyes, making himself comfortable; It was a good thing today was his day off.


End file.
